The proposed investigation continues and extends experiments currently in progress in my laboratory that indicate that the zona incerta (ZI) and ventral thalamus may contain neurons and/or their processes specifically concerned with behavioral responses (such as eating or drinking) to certain glucoprivic or hydrational challenges. Lesions in this portion of the brain have been shown to abolish ingestive responses to specific classes of experimental stimuli (e.g., cellular glucoprivation produced by 2-deoxy-D-glucose) while leaving the response to others (e.g., insulin) intact. The proposed extensions of this research are intended to provide further evidence on the behavioral specificity of the effects of these lesions by investigation of behavioral responses to a broad range of stimulus intensities; investigate the possibility that catecholaminergic pathways may play a unique role in the behaviors under study; and determine the influence of higher-order visceral afferents. BIBLIOGRAPHIC REFERENCES: Hennessy, J.W., S.P. Grossman, and M. Kanner. A study of the etiology of the hyperdipsia produced by coronal knife cuts in the posterior hypothalamus. Physiol. Behav. 18:73-80, 1977. King, B.M. and S.P. Grossman. Response to glucoprivic and hydrational challenges by normal and hypothalamic hyperphagic rats. Physiol. Behav. 18:463-473, 1977.